We can make any class lifecycle aware by passing the Lifecycle from the activity to the required class.
Example
class TimerClass(
private val context: Context,
private val lifecycle: Lifecycle
) : LifecycleObserver {
private lateinit var countDownTimer: CountDownTimer
init {
/**
* Attaching the observer with the activity lifecycle so that we will be notified whenever
* any of the lifecycle method gets called
*/
lifecycle.addObserver(this)
}
/**
* Starts a timer from 60 secs
*/
fun startTimer() {
countDownTimer = object : CountDownTimer(60000, 1000) {
override fun onTick(millisUntilFinished: Long) {
/*
Showing the toast only if the activity is started
*/
if (lifecycle.currentState.isAtLeast(Lifecycle.State.STARTED))
Toast.makeText(
context,
"Time ${millisUntilFinished / 1000}",
Toast.LENGTH_SHORT
)
.show()
}
override fun onFinish() {
}
}
}
/**
* Whenever the Activity is in/ goes to onStart state we will restart the timer ( we cannot pause/resume count down timer)
*/
@OnLifecycleEvent(Lifecycle.Event.ON_START)
fun onStart() {
countDownTimer.start()
}
/**
* Whenever the activity goes to stop state, we will cancel the timer
*/
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
fun onStop() {
countDownTimer.cancel()
}
}